By Robin Street
Geographic Range
The spiny dogfish inhabits the temperate and subarctic latitudes of the North Atlantic and North Pacific oceans. Specimens have been found in the Black and Mediterranean seas.
Biogeographic Regions:
arctic ocean 
(native ); atlantic ocean (native ); pacific ocean (native ).
Habitat
Spiny dogfish exist in an oceanic environment of depths from the surface to 400 fathoms or more. They prefer a temperature range of 6-11 degrees centregade.
Physical Description
(6.82 to 20.02 lbs)
The spiny dogfish can be recognized by its two dorsal fins, each with a spine; second dorsal is smaller than the first. Pectoral fins posses curved margins and rounded free rear tips. These sharks have narrow anterior nasal flaps. The teeth are oblique and smooth with a notch on the outer margin. Color is slate grey to brown above (often with scattered small white spots) and light grey to pure white on the belly. An albino was reported in Norwegian waters.
Some key physical features:
bilateral symmetry .
Reproduction
This shark is ovoviviparous. Males reach maturity between 80-100cm in length or at around 11 years of age; females mature at100-124 cm or in 18-21 years. Mating takes place during the winter months. As soon as the eggs are fertilized, the female secretes a thin, horny, transparent shell around them. The shells suround several eggs at once and are called candles. Gestation lasts between 22-24 months. Litters range between 2-11 pups and are between 20-30 cm at birth. They live for as long as 25-30 years.
Behavior
Spiny dogfish are gregarious fish that form large schools of hundreds to thousands of sharks, often composed entirely of the same size or sex. The schools have north-south coastal and on-shore off-shore movements that are not completely understood. The name "dogfish" was adapted by fishermen who referred to the schools of them chasing schools of smaller fish as "packs".
Key behaviors:
natatorial ; motile .
Food Habits
Spiny dogfish prey on bony fishes, smaller sharks, octopuses, squid, crabs, and eggcases of sharks and chimaeras.
Economic Importance for Humans: Negative
This fish causes tremendous damage when packs of them become entangled in commercial fishing nets.
Economic Importance for Humans: Positive
This species is used for its oil and as fish meal. It is also a popular labratory animal. In some areas (Europe more than the U.S.), it is a popular food fish.
Conservation Status
No special status.
For More Information
Find Squalus acanthias information at
Contributors
Robin Street (author), University of Michigan.
